kgorman

mobil-1 0w40

Bill Wagner

I'm switching to Shell Rotella T 5W-40 synthetic at the next change. I used to use Mobil 1 15W-50, but all the hoopla surrounding the excessive engine wear on the new oils with reduced zinc levels (those with the SM specification) and all the associated failures made me think "let someone else be the guinea pig....not me."

The new oils have reduced zinc and phosphorus levels and are replaced by boron. On older cars, this is causing excessive wear problems, sometimes within 1000 miles. My thinking is that even though many cars will not show these problems immediately, how will they do in say, 10,000 or 20,000 miles compared to the older oils? Supposedly Mobil 1 has increased their Zn and P levels in a newer release of Mobil 1 15W-50, but I'm not sure how to tell the newer versions with the SM spec from the older ones, so I'll try out the Rotella with the old SJ and SL specs. Unfortunately, even the Rotella is supposed to be reformulated to meet the SM spec in the near future.

jeff522

Like Springer3 I was told that changing oils could be hard on the seals. About 6 years ago she started to devlope multipul oil leaks, and smoke alot. The engine was torn down to change all the seals, rings, and to do top a end rebuild. I switched her to Mobil-1 and have been using it eversince. Of course shortly after all the work was done is when a leak devolped where the two sending oil lines join at the right rear wheelwell.

Stewart H

Mobil 1 Motorsport, 15W 50

N51

I use Amsoil marine diesel oil in my ag diesels. The primary benefit is to nullify the build up of acids in off-road, high sulfur fuels. Rotella is an excellent alternative. As an aside, years ago I switched to Amsoil's synthentic grease. Far fewer failures, and I don't miss torching out spent bearings.

wsybert

Mobile 1, 10w40 High Mileage
I am looking at changing to Mobil 1 Racing 4T 10w40. It has higher levels of P and Zn and added Boron. Better wear protection.

Bearclaw

On the topic of the thread: I believe, when they are both brand new, a really good top-shelf dino oil is equal to a synthetic in lubrication - and this probably holds true for as long as we would typically keep it in our cars, since we probably change it more often on average than the public at large. But the most important factor for me is a synthetic's ability to withstand "adverse events" - namely, an overheating situation that would cause a dino oil to fail and serious damage to occur (piston scuffing, etc.). This makes the case for synth's in itself. As far as leakage, I can honestly say I have never had an engine whose leaks were made worse by synthetics. I have changed over probably a dozen engines over the years, and never found this to be the case. If it leaked before, it still will. If it was dry, it will stlll be dry. If you do find a leak after changing, chances are it's from a bad seal that was sludged over on the inside, and the cleaning properties of the synthetic scoured it off. I think this is a good thing. Besides, modern synths have seal-swell agents in them (and Group V oils are mostly ester-based, which have natural seal-swelling properties). This is an easy decision in my book. As far as the ZDDP levels, as long as they're "sufficient", I wouldn't lose sleep over it. Not to the point of putting in additives, anyway.

Gregg-K

I've been using Mobil 1 15-50 for 6 years now, which is what the PO used too. But in our part of Canada (Ontario) I can now only buy it in the 5-50 grade ... which I think is too thin.

I've been seriously thinking of changing back to a high grade dino oil and changing my oil more frequently.

.. Gregg

JasonAndreas

The 964 was delivered from the factory filled with 5w-40 synthetic oil and I would think the majority of them in the ROW are still running around with 0w and 5w.

Gregg-K

Don't know what to say about that, Jason. For temperatures above 50F, my Owners Manual calls only for Synthetic grades 10W40, 15W40, or 15W50. And that was before the latest oil formulations reduced the Zinc etc content....

I don't see any downside to staying with a high quality 15W50 and keeping it changed.
.. Gregg

JasonAndreas

The earliest 964 oil TSB (for North American carbon formation problems) that I have goes back to 1992 showing Mobil-1 5w30 as approved for all-season use. Obviously the oil formulations have changed so the list is useless but I'll post it anyway.



and the temperature-range was type specific



The ZDP reductions began in 2003 (or at the very least were tested back in 2002/2003), here's the latest (January 2007) mobil 1 approved list. Whether or not there is a real problem is another story.



Except for winter driving I don't know of any either.

Tom W

As Bill mentions above, Mobil 1 changed the additives in the 15-50 oil. The race shop that maintains my car no longer recommends it as the reduced additives lead to increased rod bearing wear. I've been instructed to use Red Line in my car. (We found excessive bearing wear after only 15-20 hours on my motor when the M1 15-50 was used.)

dcbailey

Amsoil 10W40

JasonAndreas

All the recent technical papers and testing reports (SAE, ASTM, etc.) are saying that the reduced levels could only possibly be problematic on initial engine break-in. After that its not supposed to be an issue. (I'm staying out of this one -- there's too much religion already)

Bearclaw

Jason, was this from '92-on perhaps? My '91 still has the "Shell Factory Fill" sticker in the engine compartment.

I talked to one of the Red Line chemists (who happen to also be a 'Porsche guy'), and ended up liking their 10W-40.

I think the viscosity is another place where "religion" comes in: you either believe in a 0W or 5W as the low number for easy flow on cold starts, or you believe in a 15W or 20W for what I would call "viscosity safety". As long as it's synthetic, I doubt you could go too far wrong either way.